We study the interconnection of Web document caches via ATM and IP
networks. In this perspective, a document query travels trough
several caches before reaching the document home server. If one
intermediate cache has the queried document, it immediately sends it
back and the query ends. There are several challenging problems to be
solved. One is how to organise those caches : a hierarchical struture
has a smaller latency than a flat one, on the other hand it introduces
traffic bottlenecks. A second challenge is how to reliably transport
data between caches : TCP, the Web transport protocol, limits the
amount of unacknowledged data in transit and this limit must be small
in IP compared to ATM. Therefore, traffic control between IP and ATM
is critical to achieve good performances. Finally, typical drawbacks
of caching like staled documents, false statistics and security must
be addressed in this context.

We have installed a proxy HTTP server on a machine connected both to
our ATM network and to the Internet over an ethernet connection.

To see the effect of the cache try to download the following file
twice (this demo only makes sense if you have an ATM connection to our
HTTP proxy):